Zoir on "Are you sure you want to do this? Please Try Again."

Hello!!

We are new to wordpress, and we have been buying some themes in theme forest.
All of them have worked perfectly, yet now we bought a new one called: Cobra
Link below:

http://themeforest.net/item/cobra-portfolio-photography-wordpess-theme/6897826?WT.ac=solid_search_item&WT.seg_1=solid_search_item&WT.z_author=Serzh

Upon uploading the theme's .zip we get " Are you sure you want to do this? Please Try Again."
We have tried several solutions, from deactivating all plugins and themes, to checking each of the folders in the zip, in order to clear all the inner zips; as some suggestions over the net say.

Yet we havent been able to make it work. And its a long shot to get their creator to contact us back.

Can you help us? Please??

Thank you!!!!